Advances in the chemistry and practical applications of metal-organic compounds relies on the development of new ligand systems. For example, advances in the development of catalysts for asymmetric organic synthesis and carbon-hydrogen activation; models for active sites of metallo-proteins; crown ethers, cryptands, and spherands for the selective complexation of closed-shell cations; high-affinity ligands for transition metals; and oxygen transport and storage systems are attributable to new ligand systems.
Numerous phthalocyanine (i.e., tetrabenzoporphyrazine) and porphyrazine (i.e., tetraazaporphyrin) compounds have been formed by complexing different elements within the macrocyclic cavity of these compounds, i.e., the two hydrogen atoms within the cavity are replaced by an element, such as a metal ion or metalloid. The resulting coordination compounds are widely used in industry as dyes and colorants, as oxidation catalysts and as photoconductors. ##STR2##
Polymeric phthalocyanines also are known. For example, 1,2,4,5-benzenetetranitrile, 1,4-bis-(3,4-dicyanophenoxy)benzene, and, 1,4'-bis(3,4-dicyanophenoxy) biphenyl each have been incorporated into polymeric phthalocyanines by crossover macrocyclization in a reaction with other 1,2-dinitriles. Cross-over macrocyclization is disclosed in J. Elvridge et al., J. Chem. Soc., page 3536 et seq. (1955), incorporated herein by reference and referred to herein as the Linstead macrocyclization procedure.
These polymerization reactions typically provided complex, nonhomogeneous polymers of ill-defined structure. For example, the preparation of polymeric phthalocyanines by the well-known Linstead macrocyclization procedure is complicated by undesirable side reactions which lead to the formation iminoindoline, carboxamide, carboxylic acid and s-triazine by-products. In addition, the formation of various isomers is an additional disadvantage that increases in significance as the molecular weight of an oligophthalocyanine increases. Furthermore, many of the polymeric phthalocyanines are highly insoluble in organic solvents, thereby precluding purification, characterization, and, ultimately, manufacture, fabrication, and practical application.
Alternative routes for preparing polymeric phthalocyanines exist. For example, phthalocyanine tetracarboxylic acids and tetraamines have been polymerized via the formation of amides or benzimidazoles. Methacrylate-substituted phthalocyanine compounds have been polymerized by free radical techniques, and various polymers having halide substituents have been functionalized with phthalocyanines having amino groups. Arrays of cofacially stacked phthalocyanines also have been assembled by linking metallophthalocyanines via shared axial ligands.
Notwithstanding the previous work with respect to phthalocyanines and polymeric phthalocyanines, there still is a need in the art for novel phthalocyanine or porphyrazine compounds, and polymers derived therefrom, that are easy to manufacture, that are of defined structure, and that can be designed to exhibit predetermined properties such as color, solubility, conductivity, and magnetic moment. The preparation of such porphyrazine-based polymers first requires the development and synthesis of suitably substituted porphyrazine compounds to act as monomers or precursors.
The present invention, therefore, is directed to porphyrazine compounds which can be selectively functionalized at the periphery with up to eight heteroatom moieties, either the same or different, for their intrinsic properties. The porphyrazine compounds have the inherent capability of complexing one element (M) within the center of the molecule (i.e., the macrocyclic cavity), and, if desired, can have the further capability of complexing one, two, three or four additional metal ions (M.sup.1), either the same or different, to the periphery of the porphyrazine compound. The resulting multimetallic porphyrazine compounds then are used to prepare porphyrazine oligomers or polymers by edge-sharing the peripherally complexed M.sup.1 metal ions between adjacent multimetallic porphyrazine compounds, as illustrated by the porphyrazine oligomer of structural formula I, wherein two metalloporphyrazine monomers are linked by an edge-shared, peripherally complexed octahedral metal ion M.sup.1. ##STR3##
In porphyrazine oligomer I, M is 2H or is an element (e.g., a metal ion or a metalloid) capable of being complexed within the macrocyclic cavity, M.sup.1 is a metal ion capable of complexing with the moiety X, X is a moiety having sulfur, oxygen, nitrogen, phosphorus, selenium or tellurium atoms for complexing with M.sup.1, Y is a noncoordinating moiety, e.g., a hydrocarbon moiety (including hydrogen) or any other moiety that is incapable of coordinating with an M.sup.1 metal ion, and L is a ligand that completes the coordination sphere of M.sup.1. By appropriate choice of element M and metal ion M.sup.1, by varying the number and identity of peripheral moieties X (i.e., having more than two X moieties per porphyrazine compound, such as four, six or eight X moieties), by changing the identity of ligands L that complete the coordination sphere of the peripherally complexed M.sup.1 metal ions, by changing the coordination sphere of the peripherally complexed M.sup.1 metal ions, and by varying the identity of the noncoordinating Y moiety, a broad range of novel multimetallic porphyrazine compounds, oligomers, and polymers can be prepared.
The present porphyrazine compounds provide multimetallic porphyrazines and porphyrazine-based oligomers and polymers that are distinct from, and have superior properties over, existing porphyrazine and phthalocyanine compounds, and oligomers and polymers derived therefrom. The improved properties result, in part, from direct contact between the peripheral heteroatom moieties and the pi (.pi.) system of the porphyrazine macrocycle, the ability to control physical and chemical properties of the compounds by a judicious selection of the type and number of heteroatomic moieties, and their geometric relation at the periphery of the compound. The peripherally complexed M.sup.1 metal ions interact with the pi (.pi.) system of the porphyrazine macrocycle to provide a varied metal to metal (i.e., M to M.sup.1) communication which is manifested by charge and spin delocalization, the formation of high spin molecules, and multi-level redox chemistry. Such properties form the basis of new colorants, new imaging agents, and improved magnetic materials and conductors. Additionally, porphyrazine oligomerization via peripherally complexed M.sup.1 metal ions provides, in many cases, homogeneous polymers of known structure and predetermined molecular weight.
In addition to multimetallic, porphyrazine-based oligomeric and polymeric compounds, multimetallic complexes prepared from a porphyrazine capable of complexing with multiple metal ions are important in the fields of electron transfer, magnetic interactions, optical phenomena, excited-state reactivity, biomimetic chemistry, mixed valency and ionophoric activity. Investigators previously have studied polynucleating macrocyclic ligands, and in particular have studied some porphyrins and phthalocyanines functionalized with moieties capable of coordinating with metal ions.
For example, porphyrazine compounds having all sulfur or all hydrocarbon moieties positioned at the eight peripheral .beta.-pyrrole positions have been prepared. The synthesis of porphyrazine-2,3,7,8,12,13,17,18-octathiolate, depicted as the compound of structural formula II, has been reported by Velazquez et al. in J. Am. Chem. Soc., 115, pages 9997-10003 (1993). ##STR4##
Compound II is a porphyrazine compound bearing four dithiolene moieties (i.e., eight sulfide (S.sup.-) moieties), peripherally, at the .beta.-pyrrole positions. The porphyrazineoctathiolate II, therefore, contains a porphyrazine ring system substituted with eight thiolate sulfur atoms at the .beta.-pyrrole positions, which permits completing of four metal ions to the periphery of compound II in addition to one metal ion within the macrocyclic cavity of compound II. In other words, each of the four peripheral dithiolene moieties can be complexed with a metal ion. Compound II can behave either as a tridentate ligand at the periphery of the molecule (e.g., compound of structural formula III) or as a bidentate ligand at the periphery of the molecule (e.g., compound of structural formula IV). ##STR5##
Other publications relating to porphyrazine-2,3,7,8,12,13,17,18-octathiolate include:
C. T. Schramm et al., "Octakis(alkylthio)-tetraazaporphyrins", Inorg. Chem., 19, pages 383-385 (1980);
C. S. Velazquez et al., "Metal-Encapsulated-Porphyrazines: Synthesis, X-Ray Crystal Structure and Spectroscopy of a Tetratin-star-Ni(porphyrazine)S.sub.8 Complex", J. Am. Chem. Soc., 112, pages 7408-7410 (1990); and
C. S. Velazquez et al., "star-Porphyrazines: Synthetic, Structural, and Spectral Investigation of Complexes of the Polynucleating Porphyrazineoctothiolato Ligand", J. Am. Chem. Soc., 114(19), pages 7416-7424 (1992).